CHARLOTTE – The NFL season has often been described as a marathon and not a sprint, but really it's both.

When the Panthers exited the tunnel and entered the field at Bank of America Stadium for their preseason home opener Friday night, it had been 23 days since they reported to training camp at Wofford College. It also was 23 days before they'll do it for keeps in the regular season opener against the Dallas Cowboys.

While it already feels like a long journey, it's actually only the beginning – and for some, it's already ended. A few camp bodies who reported to Spartanburg on July 25 are no longer on the roster, and two more (cornerback Ross Cockrell and safety Damian Parms) have seen their season end before it began courtesy of a season-ending injury. And over the 23 days that follow Friday's 27-20 victory over the Miami Dolphins, at least one player a day on average - though most of the casualties will be concentrated on cutdown day – will see their journey end as well.

With all that's on the line, even before the Panthers post a single crooked number in the win or loss column, the breakneck pace around the bench area comes as no surprise.

"Fast! Speed!" defensive coordinator Eric Washington screams to his players just before kickoff. "Everything is fast!"

That, in a nutshell, is life in the NFL.

Washington, at age 48, is a rookie of sorts. He's worked the bench area countless times during a tenure as defensive line coach that started in 2011, but Friday was his first game in front of the home fans in his new role.

One of his students, 23-year-old linebacker Jermaine Carter, is a rookie of a different sort. The Panthers' fifth-round draft choice gets the honor of being on the kickoff coverage unit to open the game, and the adrenaline is flowing as if it were the Cowboys game. After a touchback so typical in today's game, Carter comes back to the bench area having taken care of his responsibility but having had really no chance to make a football play.

Still he is breathing heavy, trying to catch his breath after what has to be a breathless moment for a rookie. Soon he's hearing Washington's booming voice again while sitting with his fellow linebackers, getting instruction from first-year linebackers coach Steve Russ as Washington rushes down the line.

"First third down! Excellent job!" Washington says. "Great concentration!"

Within seconds, the continual concentration on what's next pauses for celebration. Defensive players rise from the bench as running back Christian McCaffrey, an expectant rookie this time last year, takes a handoff and turns it into a 71-yard touchdown.

High-fives flow, but nearly before the big screens at either end of the stadium finish showing the replay, the offensive line takes a seat on the bench and begins taking instruction from longtime line coach John Matsko.

"That's the way to get it started up front," Matsko shares with his group, which features two different starters than expected thanks to injuries. One of those starters, left guard Greg Van Roten, made the block that sprung McCaffrey.

Not everyone noticed, but Matsko sure did. McCaffrey, too. As the offensive line begins preparations of its next series, McCaffrey briefly interrupts to slap the hand of each lineman in appreciation.

The next few minutes aren't as joyous. The defense does stiffen in time to hold Miami to a field goal and hold the lead for Carolina, but it was a tough set of snaps. The Panthers perennially rank among the league's sack leaders, so the Dolphins as many teams do dink and dunk their way down the field with a series of quick-release passes by quarterback Ryan Tannehill.

"Ball's coming out quick!" first-year defensive line coach Brady Hoke says as the defensive line makes its way back to the bench. "Hands high!"

Their latest in a never-ending string of classroom sessions is interrupted when quarterback Cam Newton is intercepted. The defense digs in to force another field goal, a kick that kicks Newton into high gear. As he's often done since his rookie year in 2011, he quickly loosens up by firing a few bullets at the team's assistant equipment manager, Greg Almond, before reentering the game.

Almond has faced the firing squad so many times before but the game doesn't slow down for him. He braces for impact as the ball barrels toward him.

"I've fallen a couple of times," said Almond, who has an impeccable track record for making the grab. Unlike a bullpen catcher when a relief pitcher warms up down the first base line at a minor league game, Almond has no one backing him up.

"Just do the best I can," Almond says.

"If they get in a two-minute situation, don't get rattled," longtime assistant turned defensive backs coach Richard Rodgers shares with his unit. "Keep everything in front of you."

Soon, the defensive backs are back on the field. The Dolphins enjoy a brief 9-6 lead, but they won't lead again after Newton wraps up his evening with a 27-yard touchdown pass to rookie tight end Ian Thomas.

The defensive backs then do their part, and the Panthers head to the locker room up 13-9.

"Great job!" Rodgers says after the defense forces a punt, then returns to the bench area for a brief moment before a kneel-down by the Panthers offense ends the half. "That's what we do!"

In the second half, they do it all over again – with a twist that reminds that this is the preseason, that this is only an early chapter in the 2018 season. The players keep playing, the coaches keep coaching, but many of the principals turn into engaged spectators.

While the group of players having to battle the hardest to make sure their journey doesn't end try to take advantage of precious reps, Newton and linebacker Luke Kuechly show support in their own unique ways.

Newton bounces up and down and smiles after the defense makes another stand. Kuechly carries as many cups of Gatorade as his hands will hold over to the linebackers coming off the field. He hides his disappointment when there are no takers.

Newton screams and smiles as the offense extends the Panthers' lead. Kuechly maneuvers behind the bench, helping equipment manager Don Toner as he rifles through some extra helmets looking for something to help David Mayo. Kuechly smiles as wide after the equipment adjustment as Newton does on running back Elijah Hood's touchdown that seals the victory.

The players return to the locker room, then return to their homes as midnight fast approaches.

After a break that feels about as long as a street-side handoff at a water station, they'll return to the marathon. In a sprint.